Help me design a 350

Discussion in 'Small Block Tech' started by vonhef, Jun 24, 2018.

  1. hugger

    hugger Well-Known Member

    It's advertised as 10.1 yes, but just dropping it in a 350 isn't going to net you 10to1 comp ratio, that was what I was eluding too. The deck will need to be cut etc, lot of guys buy pistons based in what they are advertised as then the Mach shop just cuts .008 off the deck to square it then on goes the .041 felpro gasket and guess what you now have 9.3 to 1

    You can run 10.1 to even 11.1 on pump gas if the cam timing is there to support it.
     
  2. Mart

    Mart Gold level member

    Ethan said it...^^^...X2
     
    Dano likes this.
  3. alec296

    alec296 i need another buick

    Yes. The 340p piston need to be about .018 below deck with a .040 gasket at .030 overbore to be about 10.05 compression. That’s .040 off deck of block. If 340p replacement piston reaches.058 below deck( about stock factory) you will have 9.3 compression.
     
  4. Paul Stewart

    Paul Stewart Well-Known Member

  5. alec296

    alec296 i need another buick

    24 cc dish rough guess, 1.805 compression height. .030 below deck then the 340p . Expect about 7.8 compression.
    You would be better off with the uem-1734 v6 piston which is a flat top. Still sitting.090 below deck. Nets about 9.65 . Same piston pin. My guess is that sitting that low gives up 20-30 hp.
    A piston with 1.855 compression height would be closer to top of block.
     
  6. vonhef

    vonhef Well-Known Member

    I am from southern Oklahoma. I might be interested in a short block from Texas :)
     
  7. Paul Stewart

    Paul Stewart Well-Known Member

  8. alec296

    alec296 i need another buick

    Yes, custom forged would be best.
     
    70skylark350 likes this.
  9. 36racin

    36racin Platinum Level Contributor

  10. 70skylark350

    70skylark350 Jesus loves you unconditionally

    JE makes a nice custom piston but they cost $1,200.00 rings included. The Autotec's from Jim seem like a bargain at just under $800.00, then rings are another $169.00, but you have to overbore the rods .005 to accept the wrist pins.

    My machine shop strongly recommend forged pistons over cast.
     
  11. 70skylark350

    70skylark350 Jesus loves you unconditionally

    Im right there with you on the machine shop costs. Im at about $3,000 plus parts for an assembled short block. I thought I was going to build this engine complete for about $2,500.00 before I started..... lol, wow was I shocked. Last engine I built was about 15 years ago, and it was a 351 Ford.
     
  12. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    They use to be $649(rings included) when they sold them with the .945" wrist pins(.005" over the standard sbb size), now that they are $699 Rings included, they have the .940" sbb wristpin size now. IMO they raised the price $50 for the custom sbb wristpin size they have made for them now because no one made that size in a performance wristpin until they had them made.

    I think you have the AutoTec 455 pistons JW sells confused the sbb 350 pistons? The 455 pistons don't include the rings and the sbb AutoTec pistons do.
     
  13. alec296

    alec296 i need another buick

    Jim is doing 350 Pistons also. And Mike Phillips at AM&p is also doing 350 pistons.
     
  14. 70skylark350

    70skylark350 Jesus loves you unconditionally

    Im just telling you what Jim told me, maybe he was confused thinking I wanted 455 pistons? I have the PM between him and I
     
  15. 70skylark350

    70skylark350 Jesus loves you unconditionally

    See below, this is copied and pasted form my PM conversation with Jim.:

    "Dave, the Autotec pistons are Forged 4032 Alloy

    Cost is $679.00 plus shipping

    This is a "shelf stock" Piston that I do for the 350 Buick It's specs are as follows

    Bore 3.830
    Compression distance 1.895
    Symmetrical valve reliefs .195 deep at 12*
    Total dish/valve relief CC is 16
    .745 Pin (comes with pins and locks)
    Performance 1/16-1/16-3/16 ring package (rings not included)

    Piston weight is 495 grams

    Compression with your specs would be 9.93-1, which is what I would build the motor at, but at your request they will lower the CD to leave the pistons .020 in the hole, which will drop the compression to 9.54-1.

    These are custom forged pistons I had made for motors just like yours.. I am aware of the v-6 pistons (the ones your guy found that will leave them .050 in the hole) and I felt that a custom pistons was needed for this motor.. there are many benefits vs the TRW stock replacement piston he is talking about.. Correct Compression distance, which is a big factor in detonation control and power output, performance rings, valve reliefs ect ect.. they are worth twice as much, if that is the cost difference.

    We also can shrink the bore size to 3.810 for no charge.

    It takes 3 weeks to have these made out in California.

    Thanks"
     
  16. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    https://www.buyracingparts.com/pist...totec-forged-350-buick-dished-piston-kit.html

    Not sure when you contacted JW, but the sbb 350 pistons are available with the standard sbb size of .940" now as well as the .927" sbc size because that is how the Molnar rods are made with.

    I'm sure that the .745" is a misprint that is suppose to be .945" and the $800 was off as well plus rings are included with the sbb 350 pistons when you buy them from the link, should be the same with JW? For $679 if they came with the rings is a good deal, otherwise for an extra $20 I would buy them from the link.
     
    Last edited: Jun 28, 2018
  17. 70skylark350

    70skylark350 Jesus loves you unconditionally

    damn it man..... I wish that I had this information before I paid $1,200.00 for custom JE pistons. I tried contacting Autotec directly both by phone and email and got no response, so I went thru Jim as he is a distributer for Autotec. I trusted what he was telling me was correct....
    P.S. that PM with Jim was about two weeks ago, and yes the .745 was supposed to read .945
     
  18. vonhef

    vonhef Well-Known Member

    I have ordered the short block parts... and ended up buying all of it through TA.

    Block bored .30
    Oil passages drilled
    10:1 cast pistons (probably around 9.3:1)
    TA forged rods
    212 hyd, roller cam & lifters
    billet roller timing chain set
    New front cover & oil pump
    new harmonic balancer
    and of course all the upgraded bearings & gaskets

    I hope TA will have the new heads ready by the time I am ready to assemble the top end.... we shall see.
     
  19. alec296

    alec296 i need another buick

    If your gonna get the TA heads, cancel the 212 and go to the 413 cam. If your gonna get heads that flow, make them flow. Especially if you got TA forged rods. And forged rods but cast pistons? Wanted money.
     
  20. OddfireV6

    OddfireV6 Active Member

    Buicks have teeny tiny little itty bitty oil pumps that don't have much volume. They rely on the engine having very tight clearances to prevent bleeding off what flow and pressure the pump has. Buicks (originally) ran half the bearing clearances of most other engines and had lifters that flowed only a small amount of oil up to the rocker arms. They flowed so little oil, that stem seals on the exhaust valves were unnecessary and were not used. Both of these things enabled Buicks to build....get this....13 PSI at idle and 37 PSI at 2500 RPM of oil pressure. Whooptie freakin' doo.

    Here's the problems:
    1. Modern bearings are made to fit with greater clearance than the OE Buick bearings. The bearings themselves are made larger to have about 0.0020" of clearance, which is twice the OE Buick clearance. Regrinding your crankshaft to .010", .020", etc. undersize just makes the crank exactly that size under it's original dimension. The bearing manufacturer knows this dimension and makes their bearing to fit that dimension with 0.0020" of clearance Again, too large. The only way around this is to have your crank custom ground with 0.001" less clearance than the standard undersize of .010", .020", or .030". Instead of .010", you'd specify .009", or .019" instead of .020", etc. You still run into the problem that the bearing manufacturer did not intend their bearings to run at OE Buick clearance. They did not design the bearings to run that tight, so running a modern bearing at OE Buick tightness may cause problems. Also, most machine shops do not regrind cranks precisely enough to allow for OE Buick clearance. They allow too much oval and taper to run the bearings that tight.
    2. Modern lifters (including TA) flow more oil up through the pushrods to the rocker arms than the original Buick lifters did. They seem to fit the lifter bores looser in the block too. These both bleed off oil pressure and volume. The higher flow of oil also causes oil burning past the exhaust valve stems. You may install exhaust valve stem seals to Band-Aid fix this, but it's not dealing with the actual problem.
    3. Distributor gears tend to fail.
    4. The rope crankshaft seals provided in the Fel-Pro gasket kits are too large and difficult to install. They tend to leak.
    5. Torque specs changed almost every year and were often too high. Following them exactly can break things. Buicks have thin castings that break easy. They are fragile and sensitive engines. You can't fix them with a hammer like you can a Chevrolet.
    Solutions:

    1. Get the bearing clearances as tight as you can while staying within the bearing manufacturer's specs and Buick's specs. You need to satisfy both if you can. Keep it under 0.0020" on all bearings. 0.0010"-0.0015" is preferred. Custom grind the grand if you have to. Impress upon the crank grinder how tight this engine will be so they can get the job done as precisely as possible. 0.0005" of oval or taper are ok when you have 0.0030" of clearance, not when you have 0.0010".
    2. TA may offer restricted pushrods. I do not see them in the catalog but they mentioned them the last time I talked to them. If you do not run restricted pushrods, install exhaust valve stem seals or you will burn oil badly. I'd install the seals anyway since having them with the restricted pushrods will still be ok.
    3. Mock up the timing cover with the oil pump and distributor before you install it. Make sure the distributor lines up properly to the oil pump and make sure the distributor does not push down on the oil pump. Verify the oil path to the distributor drive gear and verify the gear mesh with gear marking compound. Shim the distributor as needed.
    4. Forget rope seals. They worked fine when they were the right size and contained Asbestos but that is no more. Modern neoprene lip seals are available for both the front and back crankshaft seals. Use them. Buicks leak enough already without giving them another reason to leak more.
    5. Follow your judgement on bolt torque. Don't follow the specs blindly. If a spec sounds too high, ask someone. Ask this forum, ask TA. Mike at TA knows his stuff. That goes for anything when building a Buick engine. They are...different....and easy to ^@_(*^ up. Ask before you ^(*^*&%$ it up. Building a Buick like you'd build a Chevrolet results in a Buick that has to be rebuilt every 10,000 miles. Don't do that.
    On top of this, pay super close attention to your oil pump clearances. They must be in spec. You need that pump to push every drop of oil it can. There are mods you can do....some are controversial...
     
    Last edited: Oct 23, 2018
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